考虑短距离电缆中行波特性的振荡波局部放电定位方法

An Oscillating Wave Test Method Based on Traveling Wave Characteristics of Partial Discharges for Defect Location in Short Cables

由于短电缆中局部放电信号的入射波和反射波信号容易重叠,振荡波测试系统(oscillation wave test system,OWTS)一直以来对短距离电缆(小于500 m)的局部放电定位的精度较低。为实现短电缆中缺陷的精确定位,提出了新的振荡波局部放电定位方法:采用高带通Rogowski线圈与宽带通示波器实现局部放电信号的捕捉,并对单个局部放电信号特征频率连续小波分解与能量峰值识别算法相结合的方式,优化对局放单脉冲波形的识别,同时根据多组样本的分布情况进行聚类分析,提高短电缆缺陷的定位精度。根据所提出的方法,对64 m交联聚乙烯短电缆中制造2处缺陷,并搭建实验对缺陷进行定位。结果表明,该方式能够准确地探测出距离电缆首端32 m处及61 m处的缺陷,误差范围控制在2%,较大程度提高OWTS对短电缆的定位精度。

Oscillation wave test system （OWTS） generally has low resolution on defect location for short cables because of aliasing problem between incident wave and reflection. In order to improve location precision in short cables, this paper optimizes PD signal extraction method using high band pass Rogowski coil and wide band pass oscilloscope. An algorithm combining continuous wavelet expansion of characteristic frequency and energy-peak recognition method is proposed to improve PD single waveform recognition. Clustering algorithm based on multi-sample can achieve a more precise positioning effect for short cable. Two defects are designed in a 64 m-XLPE cable, and an oscillating waveform test system is established in laboratory to localize defects. Results show that this method can accurately detect defects at 32 m and 61 m from head end with error within 2%. It is effective to solve problem of accurate location in short XLPE cables.